Recently, in the art there have been needs for photosensitive silver halide photographic materials which provide high image quality, have good processing stability, and are available at low cost, and more particularly for those which enable to be rapidly processed.
Development of a photosensitive silver halide photographic material is usually carried out by continuously processing the photographic material with an automatic processing machine installed at a processing laboratory. Recently, however, more improved service for clients requires delivery of processed photographs on the same day as receiving unprocessed ones at photo shops. More recently, it has been escalated even to the extent that processed photographs are delivered within several hours after acceptance. Thus, there are now growing need for more rapid processing. Further, reduction of processing time leads to increased production efficiency and enables to reduce production cost, which justifies necessity for more rapid processing.
Hitherto, there have been studied more rapid processing from two aspects, namely, photosensitive material and processing solution. In color development, various attempts have been made which include processing at a higher temperature, higher pH and higher concentration of a color developing agent. It has also been known to use such additives as a development accelerator. The development accelerators include 1-phenyl-3-pyrazolidone specified in British Patent No. 811,185, N-methyl-p-aminophenol specified in British Patent No. 2,417,514, and N,N,N',N'-tetramethyl-p-phenylenediamine, specified in Japanese Patent Laid Open Publication No. 50.TM.15554. However, these methods can achieve no satisfactory rapid processing and often involve performance degradation such as increased fog.
Meanwhile, it is known that configuration, size and composition of silver halide grains affect development speed, and that especially, halogen composition is an influential factor and silver halide containing more chloride can accelerate development speed to a remarkably large extent.
In order to absorb ray of a particular wavelength for purposes of filtration, antihalation, prevention of irradiation and adjustment of emulsion sensitivity, a hydrophilic colloidal layer is colored with a dye.
It is also well known to prevent halation and/or irradiation in order to improve sharpness.
Dyes used for such purposes are required to provide such various properties as; satisfactory spectral absorption characteristics to meet applications; complete decolorization in a processing solution; easy elusion from a photographic material; no possibility to cause stain by residual color after development; no adverse effect such as fog or desensitization on a photographic emulsion; further, excellent aging stability in a photographic material and no discoloration or fading.
So far, many efforts have been made in order to find out dyes which can provide the foregoing properties, and many dyes have been proposed as such. Such dyes include, for example, oxonol dyes described in U.S. Pat. No. 506,385 and 3,247,127, and in Japanese Patent Publication No. 39-22069 and 43-13168; styryl dyes represented by U.S. Pat. No. 1,845,404; melocyanine dyes represented by U.S. Pat. No. 2,493,747, 3,148,187, and U.S. Pat. No. 3,282,699; cyanine dyes represented by U.S. Pat. No. 2,843,486; and anthraquinone dyes represented by U.S. Pat. No. 2,865,752.
The present inventors have examined various dyes in order to find out dyes having specific chemical structures, which are suitable for rapid processing in combination with silver halide having higher content of chloride enabling to accelerate development speed, and provide particularly good decolorization performance even in rapid processing. As a result, it has been discovered that the dyes having specific chemical structures can meet this object.
However, a combination of the preceding silver halide emulsion having a high silver chloride content and a dye having a specific chemical structure are liable to increase fog, and especially in silver halide emulsion having higher silver chloride content, this tendency is more remarkable.
In this connection, however, reference is made to Japanese Patent Laid Open Publication No. 60-221747 in which it is stated that an emulsion layer of a silver halide photographic material having a preceding constitution, which is hardened with a chlorotriazine hardener, can be inhibited in fogging.
Meanwhile, in producing a photosensitive silver halide photographic material comprising a combination of preceding silver halide with high content of chloride having excellent properties and a dye having a specific chemical structure, of which emulsion layer is hardened with a chlorotriazine hardener, there is found notable difference in sensitivity and gradation of a silver halide emulsion layer between coating of a silver halide photographic emulsion coating solution (hereinafter referred to as coating solution) on a support just after preparation and after aging at regular temperature. This poor aging stability at regular temperature creates a serious problem that it is difficult to mass-produce a photographic material of uniform quality.
Apparently, this is a problem inherent to silver halide emulsions having a high silver chloride content, and in addition, it may be also attributable to the fact that a dye having a specific chemical structure contained in photographic component layers affects performance of an emulsion in a coating solution which has been aged at regular temperature.
The above mentioned phenomenon is especially noticeable in the case where the preceding dye is added to a silver halide emulsion layer, but it is noted that the dye added to a non-photosensitive layer can affect adversely by diffusion between individual photographic component layers.
It is assumed that such phenomenon is also the case with a chlorotriazine hardener, though less noticeable.
Then, in order to improve aging stability of a coating solution at regular temperature, a method of adding a sensitizing dye to a coating solution was considered. This method is good approach for improvement of aging stability of the coating solution, but involves a problem of very frequent appearance of residual color stains due to the sensitizing dye.
As another technique for improvement of aging stability of a coating solution at regular temperature, a combination of a particular coupler and a particular sensitizing dye is disclosed in Japanese Patent Laid Open Publication No. 59-166955. This method was tested in combination of a silver halide emulsion having a high silver chloride content, a highly decolorant dye and a chlorotriazine hardener, but no sufficient effect was observed against gradation fluctuation, though the method proved to be effective for improving sensitivity fluctuation.
Thus, after all, tests with the known techniques were unsuccessful in obtaining any photosensitive silver halide photographic material which could meet the requirements for high image quality in rapid processing and good aging stability of a coating solution.